Fixed ResolvedMap to be compatible with primitives, like StringValue

[btw17]

When implementing a custom node, StringValue is incompatible with ResolvedValue despite being supported for nodes like TextNode. The ResolvedMap type requires that all provided keys be non-optional, so I've updated it to support optional keys.

Description

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[gemini-code-assist]

Code Review

This pull request aims to fix a type incompatibility with ResolvedMap for primitive-like objects such as StringValue by making the index signature property optional. However, this change does not solve the underlying TypeScript issue. I've provided a critical comment with a suggested fix to correctly address the type assignability problem.

[gemini-code-assist]

This change does not fix the underlying type issue. An object with optional properties (e.g., prop?: T) is not assignable to {[key: string]?: T} because the type of the optional property is T | undefined, which is not assignable to T. In this case, ResolvedValue does not include undefined.

To correctly fix the type assignability for objects with optional properties, the value type of the index signature must include undefined.

While this is a significant change to the type definition, it appears safe with respect to the current implementation of resolvePropertyValue, which does not produce undefined values. This change is necessary to correctly type the relationship between primitive objects with optional fields and ResolvedMap.

Suggested change

	export type ResolvedMap = { [key: string]?: ResolvedValue };
	export type ResolvedMap = { [key: string]: ResolvedValue | undefined };